Legend of Viking Sunstone is true?

An ancient Norse myth describing a magical gem which could reveal the position of the sun when hidden behind clouds or even before dawn or after sunset, has been the subject of intrigue for many years. But a team of scientists based at the University of Rennes in Brittany may have proven that the Icelandic tales describing a Viking ‘sunstone’ used to navigate the seas may not have been a fanciful story after all.